This is my take on the most important skills to cultivate as a web designer:

Listening and communication skills. I am listing this first because listening to your client should come first, before drawing up wire frames or creating a proposal.

Vision, big picture and planning. The designer must have ideas and direction, and the follow-through to implement them into an actionable plan for any project.

Organization and execution: The ability to take a thorough plan and execute solid, organized code to achieve the desired result.

Functionality and aesthetics: Designing websites and applications that are useful, easy and pretty for the users. Functionality ideally comes first, but aesthetics cannot be ignored as they play an important role in user-friendliness.

Patience and flexibility: Your ideas about how a project should be brought to life are never going to match up to the way things actually happen. Being flexible and patient means allowing the client to change their mind (to an extent) and being willing to push a deadline back when the scope increases.

Salesmanship: Being on the client’s side even it requires telling them they are wrong. This requires walking a fine line between being the authority and being at the service of your client. Being a doormat and being overbearing will both leave you dead in the water.

Life-long learning skills: Consuming new information and trying out new techniques and technologies to stay on the cutting edge. Ideally a web designer should always be setting a few hours aside to learn new things every week, although this may be close to impossible at times!